The present invention relates to heliostat assemblies; and more particularly to such an assembly for electro-optical systems that are preferably adapted to be mounted in pods.
Typical heliostat devices of the type of which the present invention is concerned, are constructed in a manner suitable for use on an aircraft for aiming a remote light source or spot, a concentrated image, or the like along a line of sight via an input mirror, toward a fixed mirror, which in turn directs the same via a lens through a lens barrel, toward a sensor. The input mirror is mounted on a two axis gimbal so that it can be rotated both in elevation and azimuth toward a selected line of sight.
Heretofore, in order to prevent vibration in operation and thereby causing the resulting images to "jitter" or "blur," counterweights were utilized on the elevation gimbal. In an attempt to overcome the adverse affect of the counterweight, the heliostat was revised such that the axis of the stabilizing mirror and the axis of the elevation gimbal were substantially in the same plane, and the mass of the body was distributed fore and aft of the elevation gimbal to eliminate the need for the counterweight. Such prior art devices were satisfactory and performed the function for which they were intended, under the particular requirements and conditions for which they were designed. However, flight conditions and mission requirements have become increasingly more severe such that pod mounted electro-optical systems require continually better line-of-sight stabilization. Under the most extreme of such stringent requirements, these prior art heliostats at times would tend to have a blurred or jittery image caused by vibration of portions of the assembly.
Thus, it is desirable that an improved heliostat assembly be fabricated that minimizes such jittering and blurring even under the most severe requirements.